Augustine of Hippo
The statement, "They went up on the breadth of the earth and surrounded the camp of the saints and the beloved city," does not mean that they came or will come to one place.
It is not as though the camp of the saints and the beloved city will then be located in some single place. The reference is to the Church of Christ spread throughout the earth.
Wherever she will be at that time, and she will be among all nations, which is signified by the breadth of the earth, there also will be the camp of the saints. There also will be His city beloved by God.
There all her enemies, since they too will be with her among all nations, will surround her with their cruel persecution. That is, they will oppress, trouble, and press her into distress by grievous assaults.
For her part, she will not abandon her militant state, because she is called by the name of a camp.